In the manual, it seems like the 15-inch tires just need any chains with "Class S" clearance. For the 17-inch tires, it seems like they specify the exact style (ladder-type chains), plus a particular type of chain (ovals on the sides, twisted-8 shape on the crosses), and particular height, width, and thickness of each link. Is there a particular reason they do this? Or is it just because that's the only size chain they tested the car with? I'm rather wary of chains on my car - I'd prefer not to use them. Hell, I'm from Wisconsin, that ought to satisfy California's chain requirement. In any case, I was considering getting the AutoSock instead (less chance of damaging the car, and easier to install), which I saw mentioned in some other posts, but Amazon and Tire Rack don't seem to carry the same sizes mentioned on AutoSock's web site. Thus, although AutoSock has a size for the 2165/45R17 tires (645), Amazon and Tire Rack carry sizes from 735-790 and X10-X40. Anybody know if any of those sizes will fit my tires? I don't plan on needing to use them much, but it's possible that I'll take a trip once in a while where they'd be needed.
I would speculate that they must be much more specific with the 17 inch rims because the clearance (both radially and laterally) is reduced compared to the 15 inch rims. I have a solution for this problem; I kept my gas sucking SUV to drive anywhere where chain controls might be in effect. I have a set of chains for the SUV (required by law when chain controls are on even with 4wd) but have never used them. I don't own chains for the Prius.
I looked at the autosock, but it's 1. expensive, 2. allegedly illegal in California, 3. not durable, especially on bare pavement (where it's often required in California...), and 4. not available in the right size for the 17" tires, that I've found anyway. So far, I've avoided taking my car any time I'd need to have chains - but if I have to get something some day, I may go for the Thule K-Summit, due to the relative ease of installation, and the fact that they don't wrap around the edge of the tire and are probably thus less likely to damage either the car or the rim. That said, they're freakin' expensive.
Well, I was going to hold off on buying them until I had a plan to use them (so I'd be under the 1-year warranty for as long as possible, if nothing else)... But Amazon had some for $160 "used - like new" (instead of $380 new, though other sizes range from about $300 to $475) that were returned, so I got 'em. If I end up using them some time, I'll let you guys know how they are... I figured $160 (plus an extra $17 for the right size lug nut adapter, which apparently isn't included - 17 and 19 mm are included, but not 21 mm) wasn't too bad, considering most of my friends have had to buy cables for around $50. And they usually only get two or three trips before the cables break - probably from a combination of rusting, cheap design, and being required to use them on bare pavement (stupid California...). So I'm hoping that these are more durable, and that I'm more likely to take them off if I need to drive 5 or 10 miles on dry pavement before (possibly) putting them on again, also helping them last longer - the cables are such a pain to install that we'd leave them on until it looked like there was no chance of needing them again on the same trip.
To follow up - I got the "used" Thule K-Summit from Amazon, and they look great! As most of the reviewers on Amazon note, the instructions stink (mainly just pictures, and not always clear). But once I figured out the right combination of bolt+spacer+lug nut adapter, it was pretty easy to put them on. I didn't feel like starting the car, so I jacked it up to install them; it's actually a pretty tight fit, so it's almost necessary to drive to get them fully installed (as the directions indicate - you drape it over the top and sides of the tire, attach it to the lug nut and tighten it, then drive slowly for a bit and the bottom works its way on the tire as you go). The one thing I noticed is that my "used" chains from Amazon's Warehouse Deals came with a few extra parts that weren't listed in the instructions; for example, I think an extra bolt and spacer, and two extra lug nut adapters. The manual shows that it comes with 17 and 19mm lug nut adapters; the Prius has a 21mm lug nut, so I bought that as well. However, the one I got came with 17, 19, 21, and 22mm lug nut adapters. So if anybody else needs the 21mm, I have a spare I can sell, otherwise it's back to Amazon they go... I'm wondering if maybe my pair went through a refurbishing process that replaced some of the hardware with a universal kit or something - either that, or Thule started including all sizes.
